After a final round of negotiations that stretched through the early afternoon Tuesday, Diageo PLC and Pernod Ricard SA signed an agreement to acquire Seagram Co.'s prized spirits and wine group for $8.15 billion from Vivendi Universal SA.

Diageo will contribute $5 billion, and Pernod Ricard will kick in $3.15 billion. The deal, which redistributes brands such as Chivas Regal Scotch whisky and Captain Morgan rum, is contingent on...